1. Field of the Invention
The present invention relates to a system for detecting the camber of a material rolled by a rolling mill during rolling operation.
2. Description of the Prior Art
Generally, the camber of a rolled material means a curved plane shape (lateral bend) of the rolled material occurring during rolling. Such camber exerts a bad influence upon the plate width accuracy and the rectangularization of a plane shape, thus impeding the improvement of the yield rate and of quality. This camber is caused by a non-uniformity in elongation between the right and left sides in the width direction of a rolled material. More particularly, it is caused mainly by the following factors:
(1) Difference in reduction opening between the right and left sides of a rolling mill; PA1 (2) Non-uniformity in diameter between the right and left sides of a rolling roll (local wear and local heat); PA1 (3) Difference in mill rigidity between the right and left sides; PA1 (4) Non-uniformity in temperature in the width direction of a rolled material (one-sided cooling and unevenness in temperature); PA1 (5) Off-center rolling; and PA1 (6) Wedging of a rolled material on the rolling mill inlet side.
Referring to FIG. 1, there is shown a typical example of occurrence of the camber, in which the reference numerals 1 and 2 denote upper and lower rolls, respectively, of a rolling mill; S.sub.R and S.sub.L denote reduction openings on the right and left sides, respectively, of the rolling mill; the numeral 3 denotes the section of a material to be rolled on the inlet side of the rolling mill; the numeral 4 denotes a plane of the material to be rolled; the numeral 5 denotes the section of the material after rolling on the outlet side of the rolling mill; and the numeral 6 denotes a plane of the rolled material. As is apparent from the figure, the right-hand reduction opening S.sub.R is set larger than the left-hand reduction opening S.sub.L, so that the rolled material undergoes a larger elongation on its left side than on its right side in the position just under the rolling mill, and it is curved to the right on the outlet side of the rolling mill.
Heretofore, such camber of a rolled material has been detected qualitatively by the operator, or quantitatively by using a gauge on an off-line after termination of the rolling operation. Thus, it has heretofore been impossible to quantitatively detect the occurrence of the camber on-line during the rolling operation, and therefore it has been difficult to control the operation of the rolling mill for preventing the occurrence of the camber.